Experimental Study Of Melatonin On Severe Acute Pancreatitis And The Expressions Of Chemokines MCP-1, MIP-2 In Rats

1.Experimental study of the melatonin on severe acute pancreatitis in ratsObjective To investigate the protective effects and mechanisms of melatonin on severe acute pancreatitis(SAP)and SAP associated lung injury. Methods Thirty-five SD rats were randomly divided into three groups: sham-operation group, SAP 3h, 6h, 12h group and MT-pretreated 3h, 6h, 12h group. The models of SAP were induced by retrograde injection 4% sodium taurocholate into the bili-pancreatic duct. MT-pretreated group were given 20mg/kg intraperitoneal injection. The levels of serum amylase, malondialdehyde (MDA) and myeloperoxidase (MPO) in the pancreas and lungs were tested. Pathological changes of the pancreas and lungs were observed. Results Compared with SO group, the levels of serum amylase, MDA and MPO in the pancreas and lungs significantly increased in SAP group (P<0.05 or 0.01). Compared with SAP group, the levels of plasm amylase, intrapancreatic MDA and MPO, intrapulmonary MDA and MPO markedly decreased in MT-pretreated group. The pancreatic and pulmonary injury obviously ameliorated in MT-pretreated group as compared with SAP group. Conclusions MT might have beneficial effects on SAP through scavenging of oxygen free radicals.2.Experimental study of melatonin on the expressions of chemokines MCP-1, MIP-2Objective To evaluated the effect of MT on the expression of MCP-1, MIP-2 in pancreas and lungs. Methods Thirty-five SD rats were randomly divided into three groups: sham-operation group, SAP 3h, 6h, 12h group and MT-pretreated 3h, 6h, 12h group. The models of SAP were induced by retrograde injection 4% sodium taurocholate into the bili-pancreatic duct. MT-pretreated group were given 20mg/kg intraperitoneal injection. The expression of MCP-1 mRNA and MIP-2 mRNA were analyzed by real-time RT-PCR. The expression of proteins MCP-1, MIP-2 and NF-κB were examined by immunohistochemistry in lungs. Results The expression of MCP-1 mRNA and MIP-2 mRNA were up-regulated obviously in the pancreas and lungs in SAP group. There were strongly expression of protein of MCP-1, MIP-2 and NF-κB in neutrophils, and macrophages in SAP group. The expression of MCP-1 mRNA and MIP-2 mRNA in the pancreas and lungs markedly decreased in MT-pretreated group. The expression of proteins of MCP-1, MIP-2 and NF-κB in MT-pretreated group were significantly lowered than those in SAP group. Conclusions The chemokines, MCP-1 and MIP-2, might play important roles in the pathogenesis of SAP. MT can downregulate the expressions of MCP-1 and MIP-2. MT might have beneficial effects on SAP partly through downregulation of expression of MCP-1 and MIP-2.